installed on Site Yvonne and one of 6 units on a YCV barge in the lagoon. A typical remote
station is shown in Figure 2.7. Each remote unit consisted of a Neher-White ionization
chamber and a remotely operated check source, all mounted in a waterproof housing, 3
inches in diameter by 6'/ inches long.
Each remote station was hard-wired to a central
control station (Figure 2.8). All land units were set on a range of 1 to 1,000 r/hr, except
for Stations B-60 and K-65, which were set on a range of 1 to 1,000 mr/hr. Half the units
installed on the S-6 barge were on the high range, the others on the low.
Each channel was calibrated prior to D-day, using a 200~mc Cosource for the r/hr
range anda 15-mc Co® source for mr/hr range.
Maximum field obtained using the strong-
er source was 10 r/hr. Inthe laboratory a calibration was made to 1,000 r/hr.
Two sleds with a remote detector mounted on each were to be pulled into the crater at
H+10 minutes (Figure 2.9).
Each RAMS remote station detector was covered with a plastic bag to prevent contamination of the detectors during the fallout. Strings used to tie on the bags at the fixed-field
stations were burned off by closing a bridge-wire circuit at the land control station after
fallout cessation. Bags covering the sled-mounted detectors were pulled off by the action
of hauling the sleds out of the sled shelter.
2.2.3 Portable Survey Instruments. Gamma-dose rate was measured using Jordan
AGB-500B-SR and AN/PDR-T1B portable meters. The Jordan instruments contain the
same type of ionization chamber as is used in the RAMS. All portabie instruments were
calibrated using the Rad-Safe calibration range on Site Elmer. Field readings were taken
by monitors holding the meters 30 inches above the ground and facing ground zero to minimize body-shielding errors. All 46 land stations were designated as monitoring stations.
2.2.4 Barge Stations. Large flat-topped barges were positioned at five stations in the
lagoon to provide collection areas for fallout. Coral soil was spread on the decks of the
barges to simulate the effects of soil irregularities on measured dose rates. The Soil also
prevented formation of rain puddies on deck plates, which could drain away collected fallout particles with postshot rainfall.
Sticky-pan fallout collectors were positioned on the barge decks so that the uniformity of
fallout deposition could be investigated. Figures 2.10 and 2.11 show instrumentation layouts for the three types of barges used. Positions of barges in the instrumentation array
are indicated in Figure 2.5. An estimate of the fraction of full-field dose at the center of
each barge, based on uniform deposition of fallout, is given in Table 2.2.
2.2.5 Fallout Collectors, Sticky Pans. Sticky-pan fallout collectors consisting of 8- by
10-inch flat metal trays covered with an alkyd-resin toluene solution and mounted on 2foot-square baffle plates were used for collecting fallout data.
Seventy-two fallout collectors were installed at 32 stations ashore. A typical installation is shown in Figure 2.12.
For stations in the lagoon where water depth ranges from 15 to 200 feet, collectors
were mounted on small buoys. At 87 lagoon stations a single buoy-mounted fallout collector provided the only instrumentation. One such station is shown in Figure 2.13.
Eight fallout-collector stations were installed on the reef upwind from ground zero.
Baffle plates were mounted about 5 feet above low-tide level so that they would be approximately 30 inches above high-tide level.
Clusters of sticky-pan fallout collectors were established at various locations in the
array to determine the statistical spread in sticky-pan readings, to examine the effects of
weathering on pans that could not be collected before being exposed to rain, and to calibrate
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